Cylinder lock keyhole shutter



Feb. 24, 1959' "E. LQSHLAGE CYLINDER LOCK msiaoLE. SHUTTER 2 Sheets-Sheet 1 Filed Aug. 15. 1955 Izvmvrox I ERNEST L. SCHL AGE BY 14 W 1 d. ATTORNEYS Feb. 24, 1959 v E. L. SCHLAGE 2,874,563

, CYLINDER LOCK KEYHOLE SHUTTER,

Filed Au 15, 1955 2 Sheets-Sheet 2 INVEN TOR.

J ERNEST L. SCHLAGE XBY United States Patent 2,874,553 7 CYLINDER LOCK KEYI-IOLE SHUTTER Ernest L. Schlage, Burlingame, Calif., assignor to I Schlage Lock Company, a corporation This invention relates to a keyhole shutter for a lock and has for one of its objects the provision of means for rendering a keyhole or keyway substantially dust proof.

It has been found, in areas in which contaminants, such as dust, exist in appreciable quantities in the air, that such contaminants are often blown or otherwise find their way into lock keyholes. Especially with regard to pin tumbler locks, these contaminants, even in small quantities, tend to foul the lock action and over a period of time may render it inoperative.

Dust and the like also increases wear on the lock parts, including the keyway, and the key. This wearing away of the parts may result in the serious consequence of reducing the security afforded by the lock. Either the keyway or the lock tumblers or both may become so worn that keys other than the correct one will open the lock. -In other cases the key may become so worn that it will not operate the lock to which it was originally fitted.

Heretofore, devices for covering a keyhole have taken the form of a swing cover which must be manually pushed aside from the keyhole (and held there if spring urged) in order that the key may be inserted in the lock. Furthermore, this type of cover is often more trouble than it is worth and so remains pushed aside from the keyhole where it is useless. Even in those cases where such a cover is spring urged to a position covering the keyhole, not only is opening the lock a two-handed operation, but the cover may become loose and thereby functionally be impaired.

It is therefore an object of this invention to provide a keyhole shutter which overcomes the disadvantages of prior art devices.

Another object of this invention is the provision of a keyhole shutter which allows easy access to the keyhole while preventing influx of dust and the like thereto.

A further object of this invention is the provision of a keyhole shutter which is relatively inexpensive to manufacture and install, but which is effective in preventing fouling of a keyhole.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is an enlarged front elevational view of the keyhole shutter of thisinvention in the closed position, partly broken away and in section to show internal details;

Fig. 2 is a sectional view taken along line 2-2 of Fig. 1 showing a door knob and lock associated therewith in dot-dash lines;

Fig. 3 is a sectional view taken generally along line 3-3 of Fig. 2 and showing the shutter in the open position for admitting a key to the lock;

Fig. 4 is an exploded, perspective view of the keyhole shutter of Fig. 1.

In detail, referring to Fig. 2, the keyhole shutter of this invention, generally designated 1, is adapted for use 2,874,563 Patented Feb. 24, 1959 partially in dot-dash lines. Locks such as 2 are conventionally provided with a central keyhole, and it is for the purpose of protecting this keyhole from dust and the like that this invention is devised.

Keyhole shutter 1 comprises a cylindrical, two-part housing, generally designated 6, having a top cover 7 and a bottom cover 8. Said covers have opposed, overlapping, peripheral flanges 9, 10, respectively, so that the two may he secured together to enclose a space 11 (Fig. 2). Hous' ing 6 is adapted to be secured to the face of lock 2 by screws 12, 13which extend through top cover 7, space 11, and bottom cover 8 and into the body of lock cylinder 2. Screws 12, 13 act both to secure covers 7 and 8 together and to secure them to the lock cylinder.

Covers 7 and 8 are provided with elongated entry holes 14, 15, respectively, coaxially aligned with each other and with the keyhole in lock 2. Interposed between the bottom of bottom cover 8 and lock 2 is a dust seal 16, which may be made of vinyl plastic or the like and which is also provided with an aligned entry hole or slot 17. In this manner housing 6 is secured to lock cylinder 2 in substantially dust proof relation thereto except for entry holes 14, 15, 17. Such entry holes are of slightly greater width than a key 18 (Fig. 2) to permit entry of such key through said entry holes and into the key hole in lock 2.

Mounted in space 11 inside housing 6 are a pair of opposed shutter members 20, 21. Said members are coplanar and of the general form of segments of circles having their straight edges 22, 23, respectively, in engagement along the central longitudinal plane of entry holes 14, 15. Members 20, 21 are further provided with elongated slots 24, 25, respectively, through which the shanks of screws 12, 13 extend. Said shutter members are therefore mounted for movement from a position with edges 22, 23, in engagement and closing entry holes 14, 15 (Fig. 1) to a position with edges 22, 23 spaced apart to allow key 18 access through entry "holes 14, 15 and into the key hole in lock 2 (Fig. 3).

In order to retain shutter members 20, 21 in the closed position to prevent entry of dust and the like through housing 6 and into the keyhole in lock 2, the periphery of said members is formed with a circumferential recess 26 (Figs. 2, 4) in which resides a C-shaped spring 27. Spring 27 embraces a substantial part of the periphery of each member 20, 21 and is provided with an inwardly directed end 28 (Figs. 1, 3, 4) received in a hole 29 extending inwardly from the bottom of recess 26 in one of said shutter members. Spring 27 therefore yieldably urges members 20, 21 into closing relationship wit-h respect to the keyhole as shown in Figs. 1, 2.

Recesses 26 need only be deep enough 'to retain spring 27 except at certain points 33, 34 where such recesses may be further cut into members 20, 21 to prevent binding of spring 27 during movement of said members. At 33, the recess in the top end of each member is formed deeper to allow spring 27 to maintain its circular shape while holding members 20, 21 together in the closed position (Fig. 1). At 34 (Fig. 3) recess 26 in member 20 is cut deeper to prevent the end of spring 27 from digging into the bottom of said recess.

In order to facilitate entry of key 18 between edges 22, 23 of members 20, 21 and into the keyhole in lock 2, said edges may be chamfered inwardly as at 30, 31, respectively (Fig. 2). It has also been found advisable to form shutter members 20, 21 of a material such as the synthetic, fiber forming polyamide known commercially as nylon, due to the long wearing qualities of such :material.

Having described the present invention in its preferred form, it is obvious that many changes can be resorted to V 3 without departing fromthe'spirit of the invention'and the scopeof the following claim.

I claim: A A keyhole shutter for a lock, comprising: a housing, apair of screws for securing said'housingto the'face Qt alock in substantially dust proof relation to a keyhole therein, an elongated entry hole through said housing coaxial With such keyhole, a pairgof similar, opposed, segmental members mounted in said housingfor movement from a first position with their straight edges in engage merit generally centrally and longitudinally of said opening to a second parallel position spaced'apart transversely of said opening for allowing insertion of a key through said opening, between said edges and into such keyhole, and a C -shaped spring embracing substantially morethan 180 degrees of the periphery of said members for yield ably urging said members to said first position, an elon gated aperture provided in each of said niembers'extend 4', 1 ing'-trans\ ei-sely of" said straight edges and receiving said screwstherethrough for guiding said members during said movement.

5 References Cited in the file of this patent UNITED STATES PATENTS 

